I. Basic Information

II. Technical Specifications

(1) Basic Hardware Parameters

• Model: INSUMMCU2
• Brand: ABB
• Device Type: INSUM High-end Intelligent Motor Control & Protection Unit (IMC)
• Compatible Systems: ABB MNS low-voltage switchgear, INSUM motor management system, System 800xA DCS
• Application Fields: Auxiliary low-voltage equipment of thermal power / captive chemical power plants, water treatment pump sets, HVAC fans, metallurgical conveying motors, petrochemical circulating water pumps and industrial low-voltage complete power distribution equipment
• Current Ranges: Two selectable ranges: 0.1～3.2A for low-power loads, 2.0～63A for high-power loads, equipped with built-in through-type CTs
• Rated Main Circuit Voltage: Three-phase industrial AC 380～690V

• Auxiliary Power Supply: DC24V (standard configuration) / AC230V (exclusive optional for MCU2); power consumption: 4.7W@DC24V / 8.2W@AC230V

• 
  

• I/O Allocation: 17 DI channels (15 pre-configured + 2 universal, 24VDC/10mA), 3 DO channels for contactor control (exclusively for star-delta / three-contactor startup; MCU1 only has 2 DOs), 9 LED status indicator outputs
• Mounting Method: Standard DIN rail mounting + snap-in base mounting for MNS cabinets, integrated matching for draw-out cabinets
• Protection Class: IP20 for main unit (cabinet indoor installation)
• Mechanical Features: Fanless fully-enclosed hardware with SMD industrial circuitry, excellent vibration and shock resistance, detachable modular CT assembly

• Core Functions: On-site motor start-stop logic control, full protection against overload/short-circuit/phase loss, electrical parameter acquisition, fault data logging and data upload via INSUM bus networking

• 
  

(2) Rated Electrical Parameters

• Auxiliary Power Tolerance: DC24V±10%, AC230V±15%
• Signal Sampling: Exclusive three-phase voltage measurement for MCU2 (no voltage monitoring on MCU1), line voltage range: 0～690VAC
• Digital Input: Compatible with passive dry contacts and active 24VDC signals; NO/NC contact configurable via software
• Output Contact Rating: Rated for AC230V/6A contactor coil driving, passive dry contact output
• Insulation Standard: Compliant with IEC60947 low-voltage regulation; galvanic isolation between input and output circuits with built-in surge and reverse polarity protection

• Operation Mode: 24/7 uninterrupted energized operation, applicable for unattended on-site auxiliary equipment

• 
  

(3) Measurement & Control Performance Parameters

• Protection Response Speed: Instantaneous short-circuit trip ≤10ms; inverse-time overload protection, phase loss / phase unbalance protection actuation ≤200ms
• Measuring Accuracy: Current ±0.5% FS, Voltage ±0.8% FS, Power ±1% FS
• Startup Control Logic: Built-in programmable logics for direct-on-line startup, star-delta startup, autotransformer reduced-voltage startup and soft startup; supports three-contactor topology (MCU2 exclusive function)
• Fault Storage: Equipped with non-volatile onboard Flash memory to store up to 20 historical fault records including fault type, occurrence timestamp and instantaneous fault current & voltage

• Parameter Setting Mode: Dual configuration via local pushbutton setting and remote parameter downloading over communication bus

• 
  

(4) Interface & Communication Parameters

• Bus Interface: Dedicated INSUM internal bus (interfaced with ICU communication gateway; maximum 32 MCU2 units per subnet); expandable for Modbus-RTU over RS485
• Terminal Layout: Upper/lower split screw terminals with separated routing for DI, DO and power supply to prevent miswiring
• System Networking: Multiple MCU2 units aggregate data via ICU gateway and connect to upper-layer 800xA or third-party PLC through Ethernet Modbus-TCP

• Maintenance Compatibility: Works with portable INSUM-MMI hand-held panel for on-site parameter check and fault code reading without upper-system commissioning

• 
  

(5) Environmental Specifications

• Operating Temperature: -20℃～+60℃, adapts to cabinet temperature rise in summer and seasonal ambient fluctuation in workshops
• Storage Temperature: -40℃～+70℃, withstands extreme thermal shocks during transportation and storage
• Operating Humidity: 5%～95% RH (non-condensing), suitable for humid substation environments
• Cooling Mode: Passive natural convection cooling with no vulnerable moving parts

III. Key Features

Full-range Electrical Motor Protection (Core Advantage of MCU2)

Programmable Multi-mode Motor Startup Logic

Full-parameter Online Monitoring & Fault Tracing

Real-time collection of three-phase current, three-phase voltage, active/reactive power, power factor, cumulative running hours and start-stop counts. Instant fault snapshot is automatically saved upon failure to accurately root-cause overcurrent, undervoltage or phase-loss issues.

Dual-path Parameter Configuration for Convenient Maintenance

Integrated INSUM Networking for Centralized Intelligent Control

High-reliability Maintenance-free Industrial Design

Excellent Interchangeability for Spare Part Replacement

IV. Working Principle

1. Power-on Self-test & Initialization: After energized by DC24V/AC230V auxiliary supply, the unit executes CPU self-check, CT circuit verification, bus port diagnosis and parameter loading; it switches to standby mode once all self-check items pass.
2. Primary Circuit Electrical Sampling: Built-in through-type CT samples three-phase current; dedicated voltage terminals on MCU2 collect bus three-phase voltage with real-time A/D conversion.
3. Local DI Signal Acquisition: Collect digital signals including emergency stop, local/remote switchover and auxiliary contact feedback of contactors, then store data into internal registers.

4. Logical Calculation & Protection Judgement: Compare real-time current and voltage against preset protection thresholds; inverse-time action for overload, instantaneous tripping for short-circuit and delayed shutdown for phase loss, meanwhile trigger DO output to cut off contactor control loop.

1. Start-stop Control Output: Upon start/stop commands from local panel or remote bus, MCU2 outputs DO signals following pre-defined startup sequence to drive corresponding contactors for star-delta or direct-on-line operation.
2. Local Data Storage & Bus Upload: Real-time operating parameters are cached under normal running conditions; instantaneous fault data is saved upon abnormality. Process data and fault codes are transmitted to ICU gateway via INSUM bus and further forwarded to upper DCS platform.
3. LED Status Indication: Front-panel LEDs continuously display running, fault, trip and communication failure status for intuitive on-site condition check.
4. Cyclic Steady Operation: Repeats continuous sampling-calculation-control-transmission cycles under normal status to guarantee safe round-the-clock operation of low-voltage motors.

V. Application Scenarios

(1) Low-voltage Auxiliary Equipment of Thermal / Cogeneration Captive Power Plants

On-site protection and centralized control for boiler induced draft fans, forced draft fans, circulating water pumps and condensate pumps; connected to plant DCS via INSUM networking to realize remote monitoring and interlock control of auxiliary machines.

(2) Captive Power Rooms of Petrochemical & Coal-Chemical Plants

Applied for process pumps, compressors and cooling tower fans under highly corrosive and heavy variable-frequency interference environments; comprehensive protection avoids full-line production shutdown triggered by unexpected motor outage.

(3) Municipal Water Treatment & Sewage Plants

Configured on complete MNS switchgears for intake pumps, aeration fans and chemical dosing pumps; realizes centralized intelligent motor management and becomes standard configuration for unattended pump houses.

(4) Low-voltage Complete Distribution for Metallurgy & Mining Industry